Lithium exchanged zeolite X adsorbent blends

ABSTRACT

A lithium exchanged zeolite X adsorbent blend with improved performance characteristics produced by preparing a zeolite X, preparing a binder which includes highly dispersed attapulgite fibers wherein the tapped bulk density of the highly dispersed attapulgite fibers measured according to DIN/ISO 787 is more than about 550 g/ml, mixing the zeolite X with the binder to form a mixture, forming the mixture into a shaped material, ion exchanging the zeolite X at least 75% with lithium ions, and calcining the shaped material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application based onapplication Ser. No. 10/765,018, filed on Jan. 26, 2004, which was adivisional application based on application Ser. No. 10/054,041, filedon Jan. 22, 2002, now U.S. Pat. No. 6,743,745, which issued Jun. 1,2004.

BACKGROUND OF INVENTION

This invention relates to adsorbent blends for the generation of oxygenfrom a gaseous mixture, wherein a particularly useful blend includes azeolite X blended with a binder, wherein the binder includes highlydispersed attapulgite fibers and wherein the zeolite X is lithiumexchanged, preferably after blending, and processes for the use of theadsorbent blend. This invention also relates to processes of productionof adsorbent blends prepared by the blending of zeolite X with a binderto form a blend, which binder includes highly dispersed attapulgitefibers, and then ion exchanging the zeolite X component of the blendwith lithium cations.

Zeolites are hydrated metal alumino silicates having the general formulaM _(2/n)O:Al₂O₃ :xSiO₂ :yH₂Owhere M usually represents a metal, n is the valence of the metal M, xvaries from 2 to infinity, depending on the zeolite structure type, andy designates the hydrated status of the zeolite. Most zeolites arethree-dimensional crystals with a crystal size in the range of 0.1 to 30μm. Heating these zeolites to high temperatures results in the loss ofthe water of hydration, leaving a crystalline structure with channels ofmolecular dimensions, offering a high surface area for adsorption ofinorganic or organic molecules. The adsorption of these molecules islimited by the size of the zeolite channels. The rate of adsorption islimited by the laws of diffusion.

One limitation on the utilization of zeolite crystals is their extremelyfine particle size. Large, naturally-formed agglomerates of thesecrystals break apart easily. Because the pressure drop through a bedcontaining zeolite particle is often prohibitively high, zeolitecrystals alone cannot be used in fixed beds for various dynamicapplications, such as the drying of natural gas, drying of air,separation of impurities from a gas stream, separation of liquid productstreams, generation of oxygen from a gaseous mixture, and the like.Therefore, it is desirable to blend these crystals with binder materialsto provide an agglomerate mass of the crystals, which exhibits a reducedpressure drop.

To permit the utilization of these zeolite crystals, different types ofclays are conventionally used as binders with the crystals, includingattapulgite, palygorskite, kaolin, sepiolite, bentonite, montmorilloniteand mixtures thereof. The clay content of a blended zeolite can varyfrom as low as 1 percent to as high as 40 percent, by weight, althoughthe preferred range is from about 10 to about 25 percent, by weight.

An adsorbent for separating gases comprising a binder and a crystalline,low silica faujasite-type zeolite with a silica to alumina molar ratioof 1.9 to 2.1 is disclosed in EP 0 940 174 A2. This reference disclosesthe blending of a zeolite with a conventional, dense attapulgite claybinder. The bulk density of the binder is not disclosed.

The use of a zeolite X having its base metal ions ion exchanged withlithium ions has also been disclosed. Such zeolites have been useful forthe separation of nitrogen from oxygen. A process for the use of lithiumexchanged zeolite X for nitrogen absorption is disclosed in U.S. Pat.No. 4,859,217.

One problem with zeolites blended with conventional binders is decreaseddiffusion. The larger the diameter of the zeolites, the slower the rateof diffusion of the molecules to be adsorbed. Particularly in the fieldof pressure swing adsorption, this effect is highly adverse to shortcycle time and thus to productivity. Enhanced kinetic values or fastermass transfer rates can result in lower power consumption and higheradsorbent productivity.

It has been recognized that a reduction in the particle size of formedzeolites leads to shorter mass transfer zones and shorter cycle times.This is based on the assumption that the time needed for adsorbates totravel through the macropores of the adsorbents limits the cycle time,i.e. macropore diffusion is the rate limiting step in these processes.The problem can be partially solved by adding pore forming compounds tothe zeolite/binder blend before the forming step.

Accordingly it is an object of the invention to disclose a process forthe production of an adsorbent blend, which is especially useful for thegeneration of oxygen from a gaseous stream, a process for the use ofthat blend, and the composition of the blend.

These and other objects are obtained by the processes for production,the processes of use and products of the invention disclosed herein.

SUMMARY OF THE INVENTION

The present invention is an adsorbent blend comprising a zeolite X,blended with a binder, wherein the binder comprises highly dispersedattapulgite fibers with a tapped bulk density of above 550 g/l, asmeasured according to DIN/ISO 787, and wherein the zeolite X is ionexchanged at least about 75% with lithium ions, preferably after thezeolite X and the binder are blended.

The present invention is also a process for the production of a lithiumexchanged zeolite X/binder blend, preferably used for the generation ofoxygen from a gaseous mixture, comprising

-   -   preparing a zeolite X,    -   preparing a binder containing highly dispersed attapulgite        fibers, wherein the tapped bulk density of the highly dispersed        attapulgite fibers is above 550 g/l, as measured according to        DIN/ISO 787    -   mixing the zeolite X with the binder,    -   calcining the mixture to form a zeolite X/binder blend,    -   ion exchanging the zeolite X component of the blend with lithium        ions to an exchange level of at least about 75%, and    -   drying and calcining the ion exchanged zeolite X/binder blend to        form the blend of the invention.

The invention is also a process for the generation of oxygen from agaseous feed stream containing oxygen comprising passing the gaseousfeed stream over a zeolite X blend comprising a lithium exchangedzeolite X blended with a binder containing highly dispersed attapulgitefibers, as defined above.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a zeolite X blended with a binder, which binderincludes highly dispersed attapulgite fibers and which zeolite X islithium exchanged, preferably after said blending, a process forformation of that blend and a process for use of that blend. Theinvention is based on the discovery that the adsorption rate of anadsorbent blend is dependent not only upon the size of the zeoliteparticles, but also the type and characteristics of the binder blendedwith the zeolite. It has been surprisingly discovered that the same typeand quantity of zeolite, when blended with different types of binders,produces zeolite blends which exhibit different adsorptioncharacteristics, depending upon the binder that is used. The phrase“adsorption rate” or “sorption rate” or “mass transfer rate” means therate at which an adsorbate loading in a feed stream changes over a givenperiod of time for a given adsorption separation process.

The prior art suggests that the adsorption rate of a zeolite adsorbentblend is only a function of the porosity and particle size of thezeolite crystals. It has now been surprisingly discovered that the typeof binder that is used to bind the zeolite crystals together also playsa role in the adsorption rate of the zeolite adsorbent blend.

Adsorbent aggregates or blends are formed by mixing zeolite crystalswith binder materials. Various types of zeolites may be used to formadsorbent blends including zeolite A, zeolite X, zeolite Y, zeoliteZSM-5, zeolite Beta, synthetic mordenite and blends thereof. Thesezeolites may be used singuarly or in mixtures of two or more zeolites.

Zeolites may be present in various ion exchanged forms. The particularlypreferred zeolite utilized in a blend depends upon the adsorbate that isto be adsorbed from the feed stream. When the adsorption process is forthe purification of gases, notably by pressure swing adsorption (PSA),vacuum swing adsorption (VSA), vacuum-pressure swing adsorption (VPSA)or temperature swing adsorption (TSA) methods, the preferred zeolitesinclude zeolite A or zeolite X.

In the preferred process of the invention, the zeolite utilized iszeolite X. It is specifically designed for the generation of oxygen froma gaseous mixture, such as an air stream. In a particularly preferredprocess, the zeolite X utilized is a low silica zeolite X, known as“LSX,” or low silica faujasite, known as “LSF”. The general formula forLSF is 2.0 SiO₂:Al₂O₃:1.0 M_(p)O, wherein “M” represents a metal and“_(p)” represents various numbers depending on the valence of the metal.

Zeolite X generally has a Si:Al equivalent ratio of about 1.0 to about1.25 with a more preferred ratio of 1 to 1.05. In one example asynthesized LSF has the following anhydrous chemical composition: 2.0SiO₂:Al₂O₃:0.73 Na₂O:0.27 K₂O, although the quantity of sodium andpotassium ions can vary, sometimes significantly, depending upon theprocess of manufacture of the LSF.

For the present invention a substantial percentage of the sodium andpotassium ions of the zeolite X, after having been blended with thebinder, are ion exchanged with lithium ions using conventional ionexchange procedures, such as by treatment of the zeolite X with alithium salt, preferably lithium chloride, to a level of ion exchange ofat least about 75%, preferably at least 85%, and most preferably atleast 95% of the exchangeable metal ions. Sodium and potassium ions mayremain in the zeolite X crystals.

While the most preferred lithium zeolite X component of the blend is ionexchanged up to lithium levels above 95%, useful X type zeolites can beformed wherein the zeolite is ion exchanged with lithium ions only to alevel of at least about 75%. When the zeolite X is ion exchanged tolevels between about 75% and 95%, another preferred embodiment requiresadditional ion exchange of the remaining cations of the zeolitecrystals, which generally comprise sodium and/or potassium cations, withfrom about 0.1% up to 25% of the total cations in the form of divalentcations, including, but not limited to, zinc and alkaline earth metals,such as calcium, barium, and strontium, preferably calcium, andcombinations thereof. Further useful zeolite X crystals can also beproduced, wherein the extent of lithium ion exchange is above about 75%with from about 0.1% up to 25% of the remaining metal ions being ionexchanged with trivalent cations, such as, but not limited to, lanthanumand rare earth metals. In addition, the zeolite can be ion exchangedwith combinations of divalent and trivalent ions to levels from about0.1% up to 25% of the total metal ions of the zeolite X, as long as thetotal metal ions are ion exchanged at least 75% with lithium. (Forreference purposes the term “lithium exchanged zeolite X” means azeolite X which has been ion exchanged to levels of at least about 75%with lithium ions and includes, but is not limited to, the alternativeembodiments described above.)

The lithium exchanged zeolite X of the invention has shown particularutility for the generation of oxygen from a gaseous mixture,particularly the separation of nitrogen from oxygen for industrial,commercial and/or medical purposes. Particularly preferred uses of thiszeolite X include the generation of oxygen from an air stream for use inthe medical gas industry and for industrial oxygen generation.

Binder materials are utilized to bind the individual lithium exchangedzeolite X crystals together, to form shaped products and to reduce thepressure drop during the adsorption process. However, in prior artproducts, the binder material has not enhanced the adsorption capabilityof the zeolite. In fact, conventional binder materials have generallyreduced the adsorption capacity and adsorption rate of the zeolite.Binder materials, which have commonly been utilized with zeolites in thepast, include clays, such as kaolin, palygorskite-type minerals, such asattapulgite, and smectite-type clay minerals, such as montmorillonite orbentonite. These clay binders have been used singuarly or in mixtures oftwo or more different types of clay binders.

The inventors have discovered that a particularly useful blend oflithium exchanged zeolite X and clay binder is produced when the claymaterial is comprised at least partly of an attapulgite clay which hasbeen “highly dispersed.” Generally speaking, clay particles, especiallyattapulgite clay particles, exist as dense materials with very limitedadsorption capabilities. These conventional clay binder particles aredifferent in size and shape from the zeolite particles. When formed as ablend with lithium exchanged zeolite X crystals, they tend to coat thezeolite crystals as well as occupy the space between them. Thisarrangement significantly reduces both the adsorption capacity andadsorption rate of the zeolite.

In particular, conventional attapulgite clay particles, even aftermining and work-up, are naturally formed in the shape of dense bundlesof clumped bristles. The existence of these bundles has been confirmedusing scanning electron microscopy (SEM). These bristles must beseparated or ground to permit their use as binders for zeoliteparticles. Without grinding these attapulgite clay particles to asmaller size, a non-porous layer of attapulgite clay particles iscreated in the formed zeolite X blend, preventing or substantiallylimiting, diffusion of adsorbates through the blend. The conventionalattapulgite clays that have been utilized in the past are produced bydry grinding the attapulgite clay. In this conventional process thesedry ground attapulgite clay bundles of bristles are formed in a blendwith the zeolite crystals. However, even after this conventionalgrinding of the attapulgite clay bundles, large bundles of attapulgiteclay bristles are still present. When these conventional attapulgiteclay bundles are formed in a blend with zeolite X to be utilized asadsorbents, the capability of the zeolite materials to adsorb thedesired adsorbate is not substantially enhanced.

The applicants' invention utilizes “highly dispersed” attapulgite clayas at least a portion of the binder material that is formed as a blendwith zeolite X crystals, particularly the highly lithium exchangedzeolite X crystals discussed above. The difference between conventional,dense attapulgite clay bundles and the “highly dispersed” attapulgiteclay particles of the invention can be differentiated readily throughthe use of a scanning electron microscopy. Another method to distinguishbetween conventional dense attapulgite clay and the “highly dispersed”attapulgite clay products of the invention is by the use of tapped bulkdensity measurement as determined according to DIN/ISO 787. Denseattapulgite clay binders have a tapped bulk density of only about 400g/l to about 530 g/l. In contrast, “highly dispersed” attapulgitebinders have a tapped bulk density of about 550 g/l to about 700 g/l.

Another method to distinguish between conventional dense attapulgiteclay and highly dispersed attapulgite clay products of the invention isby determining the water adsorption capacity of the attapulgite clayproducts. To determine whether the clay binder is “highly dispersed,”the clay binder is fully saturated at 50 percent relative humidity at25° C. until an equilibrium adsorption capacity is achieved. Thisprocess may take up to 72 hours. After full hydration of the clay isachieved, the clay is dried at 550° C. for at least two hours. Thedifference of the weight between the fully hydrated clay and the driedclay is the water adsorption capacity. For dense attapulgite clays, thewater adsorption capacity is below 30 percent whereas for the “highlydispersed” attapulgite clay, the water adsorption capacity is above 35percent.

While any process which produces attapulgite fibers, which are “highlydispersed” as defined above, is within the scope of the invention, onepreferred process is disclosed in U.S. Pat. No. 6,130,179, the contentsof which are incorporated by reference into this application. Thispatent fails to disclose or suggest the use of this highly dispersedattapulgite clay formed in a blend with zeolite, particularly zeolite X,more particularly zeolite LSX or LSF, and most particularly lithiumexchanged zeolite X. The process of U.S. Pat. No. 6,130,179 utilizes adispersant which disperses the individual attapulgite particles in watersuch that they remain in suspension even after other materials,including other clay and mineral species, are removed from thatsolution. Once the “highly dispersed” attapulgite clay is prepared, itis ready for use in the production of the adsorbent product of theinvention.

The binder material that is used to form the blend with the lithiumexchanged zeolite X of the invention may be comprised entirely of highlydispersed attapulgite fibers or the highly dispersed attapulgite fibersmay form only a portion of the blend. The higher the percentage of thehighly dispersed attapulgite fibers, the better performance of theoverall blend. The percentage of highly dispersed attapulgite fiber inthe binder should be at least 5% and may be up to 100% of thecomposition of the binder. Preferably the binder is comprised of atleast 30%, more preferably at least 50%, and most preferably at least90% of highly dispersed attapulgite fibers. The balance of the materialthat may be blended with the highly dispersed attapulgite fibers may beany conventional clay binder, such as attapulgite, kaolin,montmorillonite and bentonite and mixtures thereof. One process toproduce the adsorbent blend product with improved performancecharacteristics according to the invention is as follows:

-   -   prepare the zeolite X, prepare a binder, comprising at least        partially with highly dispersed attapulgite fibers,    -   mix the zeolite X with the binder to form a zeolite X/binder        system,    -   dry and calcine the zeolite X/binder system; hydrate the dried        zeolite X/binder system with water containing a lithium salt and        ion exchange the zeolite X blended with the binder to at least        about 75% ion exchange with lithium cations, and    -   dry and calcine the lithium ion exchanged zeolite X/binder blend        to form the adsorbent blend of the invention.

Other processes can be utilized to form the zeolite X/binder system ofthe invention, wherein the zeolite X is ion exchanged to at least about75% with lithium ions prior to or after the blending with the binder.Any such process for the ion exchange of the zeolite X and the blendingof that ion exchanged zeolite X with the binder of the invention iswithin the scope of the invention.

Once the appropriate zeolite X material is chosen for the givenutilization, it is mixed with the binder, which includes highlydispersed attapulgite fibers. The amount of binder can range from about2 to about 30 percent by weight, preferably from about 5 to about 20percent and most preferably in the range of about 10 percent of thecomposition as a whole, by weight. The percentage of binder present isadjusted depending on the percentage of the binder that comprises highlydispersed attapulgite clay fibers. Blends of even highly ion exchangedlithium X zeolite with conventional binders not containing highlydispersed attapulgite clay fibers require utilization of about 20percent or more of the binder material, such as a conventionalattapulgite clay. Sufficient water is retained in or added to themixture to make a formable mixture, i.e., one that can be easilyextruded or formed into a bead.

The mixture is blended using a conventional blending device, such as aconventional mixer, until a mass of suitable viscosity for forming isobtained. The blended mixture is then formed into the appropriate shapedproduct. The products can be formed in any conventional shape, such asbeads, pellets, tablets or other such conventional shaped products. Oncethe formed products are produced into the appropriate shape, they arecalcined, preferably at about 600° C., for about 30 minutes to 2 hours.

Once the shaped products are formed, they are hydrated with watercontaining a lithium salt, such as lithium chloride. The quantity of thelithium salt that is added should be sufficient to achieve the ionexchange that is desired using conventional ion exchange procedures wellknown to those in the industry. Once the ion exchange process has beencompleted to the extent required, the ion exchanged zeolite X/binderblend is dried and calcined at a temperature of about 600° C. for about30 minutes to 2 hours to form the final adsorbent blend of theinvention.

In an optional preferred embodiment, a pore forming agent may be addedto the zeolite X product/binder mixture during the mixing step toenhance the total pore volume of the end product. Among the acceptablepore forming agents are fibers, including rayon, nylon, sisal, flax andthe like and organic polymers, including corn starch, starchderivatives, lignosulfonates, polyacrylamide, polyacrylic acid,cellulose, cellulose derivatives and the like. The amount of the poreforming agent that may be added is from about 2 to about 15 percent, byweight.

Products produced by the process of the invention show improvedadsorption rates. The adsorption rate can be determined using severaldifferent methods. For example, in one process to determine theadsorption rate of the adsorbent blend of the invention, the amount ofthe adsorbed product over a given period of time is determined.

In a further process for the comparison of adsorption, the mass transferzone of the blend of the invention can be compared to that of aconventional blend under given conditions. The shorter the mass transferzone, the higher the adsorption rate.

Finally, the diffusion rate can be determined directly for certain gasesor liquids. The higher the diffusion rate, the faster the adsorptionrate.

It has been surprisingly discovered that by replacing a conventionalbinder with a binder containing highly dispersed attapulgite fibers ofthe invention, there is an improved adsorption rate regardless of whichmethod is used to measure that rate of adsorption. The improvement inadsorption rate is at least about 10 percent, and may be as high as 200percent, compared to products containing conventional clay binders, suchas conventional attapulgite clay. This improvement is especiallyimportant because of the increased cost of the highly dispersedattapulgite binder over conventional attapulgite binders.

A further surprising improvement is in the ability of the lithiumexchanged zeolite X adsorbent blend to maintain its mechanical strengtheven when the amount of the binder that is added to the mixture isreduced. Generally speaking, the more binder that is present in theforming process, the better the mechanical strength for the finishedproduct. For conventional dense attapulgite binders, this improvement inthe mechanical strength is dramatic when the percentage of attapulgitebinder within the end product increases from zero to about 20 percent ofthe composition. Products made with conventional dense attapulgitebinder of 10 percent or less are not practical as their mechanicalstrength drops below acceptable levels. It has been surprisinglydiscovered that a product produced using the highly dispersedattapulgite fibers of the invention produces an end product withadequate mechanical strength even when the quantity of the highlydispersed attapulgite binder in the end product is as low as 5 percentor less. Further, at any particular percentage of binder material, themechanical strength of a product produced using the highly dispersedattapulgite fiber of the invention is higher than for a product madewith only a conventional dense attapulgite binder.

It has also been surprisingly discovered that even when lowerpercentages of a highly dispersed attapulgite fiber are utilized in thebinder of the adsorbent product, the rate of nitrogen adsorptionincreases. This increase in adsorption can be confirmed by the processespreviously discussed. This improvement is at least 10 percent and inmany cases as much as 30 percent or more.

The binder containing highly dispersed attapulgite fibers can form ablend with the lithium exchanged zeolite X and be used for a number ofdifferent processes. The blended product made with the lithium exchangedzeolite X and the binder containing at least a portion of the highlydispersed attapulgite binder is particularly useful for the productionof oxygen. It is of considerable interest for industrial applicationsand is particularly useful in the medical gas industry for theseparation of nitrogen from oxygen. This separation is particularlysuccessful when the zeolite X product has been highly ion exchanged withlithium ions, as described above. When the zeolite X product isexchanged with lithium to high percentages, the separation of thenitrogen from the oxygen is particularly effective, even at roomtemperature.

There are a number of other processes for which this blend of a highlydispersed attapulgite clay and lithium exchanged zeolite X can beutilized and which are also covered by this invention.

These improvements are generally disclosed by the following examples:

EXAMPLES Example 1

Samples of an attapulgite clay material that is conventionally used as abinder for zeolite X products and a highly dispersed attapulgite claymaterial were tested for tapped bulk density, residual water and wateradsorption capacity. Tapped bulk density was determined according toDIN/ISO 787. (Actigel 208 obtained from ITC Floridin was used as thehighly dispersed attapulgite clay in all examples. The conventionalattapulgite clays were of different brands and obtained from ITCFloridin.)

A clay sample of about 10 grams was weighed in a porcelain crucible(weighing precision 1 mg) and heated to 550° C. for 2 hours. The samplewas cooled to room temperature in a desiccator and weighed (weighingprecision 1 mg). The weight difference led to the residual water amount.

Another clay sample of about 10 grams was weighed in a porcelaincrucible (weighing precision 1 mg) and was water saturated at 50 percentrelative humidity and 20° C. The equilibrium was reached within 72hours. The sample was weighed (weighing precision 1 mg) and heated to550° C. for 2 hours. The sample was cooled to room temperature in adesiccator and weighed (weighing precision 1 mg). The weight differenceof the fully hydrated sample and fully dried sample led to the wateradsorption capacity given in Table 1 below. The fully dried mass wastaken as 100 percent clay. TABLE 1 Attapulgite Clay Sample HighlyConventional Conventional Conventional Dispersed Dense Dense Dense ClayClay 1 Clay 2 Clay 3 Tapped Bulk 617 398 + 31 529 + 20 428 Density(g/ml) 595 (average of (average of 459 660 17 samples) 21 samples)Residual Water 22.3 25.5 21.4 25.5 as Received (%) 21.7 22.6 23.7 Water36.8 28.8 25.0 29.7 Adsorption 36.0 28.8 Capacity (%) 36.0

As is clear from the Table, the bulk density of the highly dispersedclay was significantly higher than the bulk density of the conventionaldense attapulgite clay. In addition, the water adsorption capacity ofthe highly dispersed attapulgite clay was significantly higher than thatof the conventional dense attapulgite clay.

Although the invention has been described in detail, it is clearlyunderstood that the same is by no way to be taken as a limitation on thescope of the invention.

1. A composition for the generation of oxygen from a gaseous mixturecomprising a zeolite X blended with a binder comprising highly dispersedattapulgite fibers, wherein the tapped bulk density of the highlydispersed attapulgite fibers, as measured according to DIN/ISO 787, ismore than about 500 g/l and wherein cations of the zeolite X comprise atleast about 75% lithium cations.
 2. The composition of claim 1, whereinthe cations of the zeolite X comprise at least about 95% lithiumcations.
 3. The composition of claim 1, wherein the zeolite X compriseslow silica zeolite X.
 4. The composition of claim 1, wherein the zeoliteX has a silicon:aluminum ratio from about 1.0 to about 1.25.
 5. Thecomposition of claim 1, wherein the zeolite X has a silicon:aluminumratio from about 1.0 to about 1.05.
 6. The composition of claim 1,wherein the binder comprises from about 2 to about 30% of thecomposition, by weight.
 7. The composition of claim 1, wherein thebinder comprises from about 5 to about 20% of the composition, byweight.
 8. The composition of claim 1, wherein from about 0.1% up toabout 25% of the cations of the zeolite X comprise divalent cations. 9.The process of claim 8, wherein the divalent cations are selected fromthe group consisting of zinc, alkaline earth metals and mixturesthereof.
 10. The composition of claim 1, wherein from about 0.1 to about25% of the cations of the zeolite X comprise trivalent cations.
 11. Thecomposition of claim 10, wherein the trivalent cations comprise rareearth metal cations.
 12. The composition of claim 11, wherein the rareearth metal comprise lanthanum.
 13. The composition of claim 1, whereinthe binder comprises at least about 5% highly dispersed attapulgitefibers, by weight.
 14. The composition of claim 1, wherein the binderfurther comprises a clay material selected from the group consisting ofconventional attapulgite, kaolin, montmorillonite and bentonite andmixtures thereof.
 15. A process for production of a lithium exchangedzeolite X/binder blend absorbent product comprising preparing a zeoliteX, preparing a binder comprising highly dispersed attapulgite fibers,wherein the tapped bulk density of the highly dispersed attapulgitefibers, as measured according to DIN/ISO 787, is more than about 550g/l; mixing the zeolite X with the binder to prepare a zeolite X/binderblend, ion exchanging the zeolite X component of the blend with lithiumions to a level of at least about 75%; and treating the blend to formthe absorbent product.
 16. The process of claim 15, wherein the zeoliteX is ion exchanged at least about 95% with lithium cations.
 17. Theprocess of claim 15, wherein the zeolite X comprises low silica zeoliteX.
 18. The process of claim 15, wherein the zeolite X has asilicon:aluminum ratio from about 1.0 to 1.25.
 19. The process of claim15, wherein the binder comprises from about 2 to about 30% of themixture by weight.
 20. The process of claim 15 from about 0.1% up toabout 25% of the cations of the zeolite X comprise divalent cations. 21.The process of claim 15, wherein from about 0.1% up to about 25% of thecations of the zeolite X comprise trivalent cations.
 22. The process ofclaim 15, wherein the binder comprises at least about 5% highlydispersed attapulgite fibers, by weight.
 23. The process of claim 15,wherein the binder further comprises clay materials selected from thegroup consisting of conventional attapulgite, kaolin, montmorilloniteand bentonite and mixtures thereof.
 24. A process for generation ofoxygen from a gaseous mixture containing oxygen comprising passing thegaseous mixture over the absorbent blend composition of claim 1.